Electric-circuit protector.



Patented Apr. 8, I902.

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C. A. RULFE.

ELECTRIC CIRCUIT PROTECTOR.

(Application filed Dec. 8, 1900.) (No Model.)

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UNITED STATES PATENT OFFICE.

CHARLES A. ROLFE, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE ROLFE ELEC- TRIOCOMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

ELECTRIC-CIRCUIT PROTECTOR.

SPECIFICATION forming part of Letters Patent No. 697,219, dated April 8,1902.

Application filed December S, 1900. Serial No. 38,438. (No model.)

To all whom, it may concern:

Be it known that I, CHARLES A. ROLFE, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in Electric-CircuitProtectors, (Case No. 7,) of which the following is a full, clear,concise, and exact description, refer ence being had to the accompanyingdrawings, forming a part of this specification.

My invention relates to protectors for protecting low-tensioninstruments and circuits from injury by the intrusion of unduly strongcurrents, such as power and lighting currents.

The invention relates in particular to a variety of such electricalprotectors in which is employed a body or ,mass of material which maybesaid to be softenable or fusible that is to say, sufiiciently responsiveor susceptible to a moderate degree of heat to cause it to be softenedor fused by the application of such an amount of heat. In certain formsof this style of protector the fusible or softenable material consistsof wax. In others it consists of solder. Various kinds of wax have beenemployed, as have also various kinds of solder, the composition of eachbeing sufficiently varied to cause them to be properly responsive toheat of any desired moderate degree and enduring for any desiredmoderate length of time. In these protectors the operation of the deviceis permitted by the fusing or softening of the mass or body of fusibleor softenable material, and to such end the devices are each providedwith a device for concentrating heat, so that it shall be applied to thesaid mass or body of material, and also with a circuit-controllingdevice or set of devices by which the circuit is controlled in anydesired way by the fusion or softening of said body of material.

The heat-concentrating devices and the circuit controlling devices havevaried very largely in different forms of protectors. In most instancesthe heat-concentrating device has consisted of a coil of fine wire,which would become heated and so form a heated mass or ball upon thepassage of an unduly strong current through the wire. This coil of finewire has been so associated with the mass or body of fusible orsoftcnable material that when the coil has become heated by the undulystrong current the body or mass of fusible or softenable material hasbeen fused or softened. In certain of such devices theheat-concentrating coil has been embedded within the mass or body ofmaterial, while in others the coil has been arranged outside of orsurrounding the said mass or body. In either case, however, theassociation has been so close that the generation of a moderate de greeof heat in the coil has affected the mass or body of fusible orsoftening material.

The circuit-controlling devices have usually consisted of suitablemechanisms by which the circuit is opened upon the softening or fusingof the fusible or softenable material, although in certain instancesthese circuitcontrolling devices have been such as to cause the circuitto be shunted to ground instead of being opened. In either case thearrangement is such that when an unduly strong current traverses theheat-concentrating device and causes the generation of a sufficientamount of heat to affect the mass or body of fusible or softenablematerial the circuit-controlling device operates. In the one case thecircuit is opened, and in the other case it is shunted to ground. Inboth cases the instrument on the circuit and the circuit itself areprotected from the unduly strong current, in the first instance by thecomplete stoppage of the current and in the second by its diversion fromthe circuit and instrument under protection to another circuit. As anexample of a protector of the class mentioned I might cite thatdescribed,

illustrated, and claimed in the patent to Albert Barrett, No. 445,217,of January 27,1891, for a thermal cut-out. In this patent theheat-susceptible device consists of a ball or button of wax, and theheat-concentrating mass consists of a coil of wire which is embeddedwithin the material of the wax. The coil of wire surrounds the end of aloop or shank, and a spring is arranged and held under tension by thisloop or shank. The ball or button of wax is held against the operationof the spring by a suitable support or abutment. The operation of thedevice then is ball orbutton immediately surrounding it to soften. Thespring is thereby released and operates so as to withdraw the end of theloop, with the coil surrounding it, from the interior of the ball orbutton of wax. By such withdrawal and by the continued movement of thecoil and loop as they are acted upon by the spring the ends of the coilare ruptured, so as to break or open the circuit. 4

The invention of the present application relates in particular to areleasing device for releasing the spring-actuator embodying in itsconstruction both the heat-concentrating device and the heat-susceptiblebody or mass.

The principal objects of the present invention are to provide anexceedingly simple form of responsive device of this kind, to reduce thecost of manufacture of the same, to arrange for its easy and readyembodiment in the protector and its replacement therein, and to dispensewith all connecting-wires.

In this application, for the purpose of illustrating my presentinvention, I have shown and described a form of protector similar ingeneral arrangement to a protector described, illustrated, and claimedin my application for Letters Patent No. 19,294, filed June 6, 1900. Theresponsive device of my present invention as embodied in the generalform of protector of my said other application forms an exceedinglydesirable and advantageous protective device; but I wish it distinctlyunderstood that I consider it possible to embody the said improvedresponsive device of the present application in many and various,

forms of protective devices, and hence I do not wish to be considered aslimiting myself to'i'ts embodiment in the particular form of protectorwhich is herein shown and described.

In the accompanying drawings, Figure 1 is a side elevation of aprotector embodying my present invention,,the said protector being ingeneral arrangement similar to that of my said other application, SerialNo. 19,294. Fig. 2 is an end elevation of the same. Fig. 3 is a bottomview of one of the removable holders or circuit-breaking devices of saidprotector. Fig. 4is a vertical section through the releasing deviceemployed in said holder. Figs. 5 and 6 are views, the former in sideelevation and the latter invertical section, of

. certain of the parts going to make up the constructionoof thisreleasing device.

Theform of protector shown'is intended for the protection of both sidesof an electric circuit, and to such end it is provided with two devicesA A, one for each side of the circuit.

These devices are mounted upon a suitable base 13, which is understoodto he composed of insulating materialsuch, for example, as porcelain orslate. The base Bis provided with simple forms of contact-jaws 1 1,which are arranged to receive metallic shanks 2 2, pro

vided upon the devices A A. In this way each device A is bodilyremovable from the protector by being elevated, so as to withdrawthe-shanks 2 2 from the-contacts 1 1.

Each of the devices A consists of a flat insulating-strip 3, preferablycomposed of fiber, to the opposite ends of which the shanks 2 2 aresecured. The strip 3 is provided with a spring 4, which is secured toone end of the, I

of fine wire 6, so as to be responsive to the heat generated in thatwire, asimple and desirable way being to embed the coil 6 in the mass 7,and a metallic shell or casing 8, which incloses the associated coil andmass and also the end of the hook 5. One end of the coil 6 is connectedwith the hook 5, as by being'soldered to the lower end thereof, as shownin Figs. 4 and 5, while the other end of the coil is connected to theshell 8, as by being soldered to the outside of that shell, as shownin'Fig. 4. In this way both the hook 5 and the shell 8 are electricallyconnected with the coil 6. The shell 8 is desirably made con-.

ical in shape, as shown, with the hook 5 extending from its smaller end,so that it can be partlyintroduced into the aperture in the.

holder or support 3 and at the same time will engage the rim of theaperture, so as to pre vent the shell from passing completely throughsuch aperture.

tact 9, which has one of its ends secured to one of the shanks 2 andextends lengthwise of the holder 3 from said shank along the under side.of the said support. The other end of this clip 9 is convenientlycutinto a V shape, and the edges of the V are arranged to substantiallycoincide with portions of the rim of the aperture in the support 3. Inthis way when the releasing device C is put in position in the device A,so that the hook 5 extends upwardly, and the shell Sis fitted into Theholder or support 3 is provided with a metallic clip or 0on ICC IIC

and through the aperture of the support 3 the shell will come intocontact with the flaring ends of the clip 9, and thus serve to con nectone end of the coil with one of the metallic contacts or shanks 2. Thespring 4 being connected with the other shank or contact 2, the otherend of the heat-coilis connected with this other contact 2.

A simple way of arranging the metallic clip 9 and the contact 2,connected therewith, is to stamp out of a piece of metal a singlestructure, which will comprise the clip 9, ashank 2, and portions 10 and11,'Fig. 2, which will lie above and below thestrip 3.

ture can then be secured to the strip 3 by rivets. In the same way astructure can be stamped for the other end of the device A, the saidstructure consisting of a shank 2, under and over lying portions 10 and11, the latter of which is slightly bent, so as to form a recess for thelower portion of the loop of the spring. This structure can likewise beriveted to the strip 3.

The operation of the device is as follows: Upon the intrusion of anunduly strong current upon the line the coil of wire 6 becomes heated tosuch an extent as to melt or soften the portion of the fusible mass orbody 7 immediatelysurroundingthe coil. Thisreduces the hold which thefusible or softenable mass 7 has upon the hook 5 to such an extent as toallow the spring 4 to operate and forcibly withdraw the hook 5 from theinterior of the mass 7. Upon this taking place the connection of thecoil 6 with the shell 8 is ruptured or broken, thereby disconnecting thehook 5 from the shell 8 and opening the circuit. The general arrangementof the protector illustrated and described isshown and described in mysaid other application, Serial No. 19,294 that is to say,in thatapplication there is shown a support or holder having one of its endsprovided with a spring and a releasing device so disposed as to hold thespring normally under tension and to draw against the support or holder,so that the latter acts both as an abutment for the releasing device andalso as a holder or support for the spring.

The particular novelty of my present application lies in theconstruction of the releasing device C and the manner in which this newreleasing device is connected with the terminals 2 2 of the holder 3.This novel form of releasing device can, as I have said, be em ployed invarious forms or styles of protectors other than that herein shown anddescribed. It has many advantages, among which may be mentioned thefollowing: In the first place, it is simple andinexpensive, beingcomposed of a minimum number of elements arranged and connected togetherin a simple and expeditious manner. In the next place, it dispenses withall connecting-wires, the connections being made directly with the hook5 and the shell 8, which may be termed the engaging members of thereleasing device. Again, the arrangement of the releasing device in theprotector is very convenient, so that it can be mounted in theprotector, when the same is constructed, in a minimum amount of time andcan also be replaced with equal facility. Finally, the use of allbinding-screws in the circuit-breaking devices or holders is dispensedwith, the connections be-- ing such that rivets can be employed.

IVhat I claim as my invention is 1. In a protector for electriccircuits, a releasing device comprising a metallic shell, a mass offusible or softenable material inclosed within the shell, aheat-generating device associated with the softenable or fusiblematerial so that the latter will be fused or softened by the generationof heat in the heatgenerating device, and a loop or hook engaged by thefusible or softenable mass so as to be held thereby when such mass ishard and to be released when the same is fused or softened, the metallicshell and loop or hook being electrically connected with theheat-generating device.

2. In a protector for electric circuits, a releasing device comprising ametallic shell, a body or mass of fusible or softenable materialinclosed within the shell, a coil of fine wire associated with the bodyor mass of fusible or softenable material so that the latter will befused or softened by the generation of heat in the coil of wire, and aloop or hook engaged by the fusible or softenable material so as to beheld thereby when such material is hard and to be released by the fusionor softening of the same, the said hook having its free end projectingout of the metallic shell and the coil of wire having one of its endsconnected with the metallic shell and the other with the loop or hook,substantially as described.

3. In a protector for electric circuits, a releasing device comprising aconical-shaped metallic shell, a body or mass of fusible materialinclosed within the shell, a coil of fine wire embedded in the body ormass of fusible material, and a hook having one of its ends surroundedby the coil of fine wire and the other end projected out of the saidmass of material and also out of the metallic shell, the coil of wirehaving one of its ends connected with the hook and the other with themetallic shell, substantially as described.

4.. In a protector for electric circuits, a releasing device comprisinga conical-shaped metallic shell, 2. body or mass of wax inclosed withinthe shell, a coil of fine wire embedded in the body or mass of wax, anda hook having one of its ends surrounded by the coil of fine wire andthe other end projected out of the said mass of wax and also out of themetallic shell, the coil of wire having one of its ends connected withthe hook and the other with the metallic shell, substantially asdescribed.

5. In a protector for electric circuits, the combination with areleasing device comprisinga metallicjshelha body of fusible orsoftenable material contained by the shell, a heatgenerating deviceassociated with the body of fusible or softenable material, and a loopor hook having one of its ends engaged by the said mass of material soas to be held thereby when said material is hard and to be released whenthe same is fused or softened, the heat-generating device beingelectrically connected with the shell and hook, of a contact adapted toengage the said metallic shell, and a tension device adapted to engagethe hook, substantially as described.

' 6. In an electrical protector for electric ciredits, the combinationwith a base having contact-jaws, of a holder consisting of aninsulating-strip having its opposite ends provided with contacts adaptedto fit into said contact-jaws, said strip being also provided with anaperture between its ends, a spring secured to one end of the strip andconnected with the contact at that end, a metallic strip connected withthe contact at the other end of the insulating-strip and extended to theaperture therein and constructed with portions arranged to substantiallycoincide with said aperture, a releasing device comprising a conicalshell, a metallic hook, a mass or body of fusible or softenablematerial, and a coil of fine wire, the said wire being coiled about theend of the hook and connected with the same and with the shell, and themass of fusible or softenable material being inclosed within the shelland embedding the end of the hook and the fine-wire coil, the saidreleasing device being arranged with the metallic shell in theapertiirein the insulating-strip and in contact with the saidcontact-strip extending from one of the contacts and the hook inengagement with the spring, substantially as described.

7. In a protector for electric circuits, a holder comprising aninsulating-strip having its opposite ends provided with metalliccontacts and provided with an aperture between its ends, a metallicstrip extended from one of said contact-strips along the under side ofthe insulating-strip and having a forked end, whose bifurcations embracethe aperture in the insulating-strip, and a spring secured to the otherend of the insulating-strip and connected with the contact at suchotherend,

9. In a protector for electric circuits, the

combination with a base having contact-jaws, a holder having metallictips adapted to fit into said contact-jaws and also provided with anaperture, a metallic strip'exten'ding from one of said metallic clips tothe aperture on the lower side of the holder, a spring mounted at theopposite end of the holder, an excesscurrent-operated device having ametallic shell adapted to fit into said aperture and also adapted torestagainst the said metallic strip, and a connection betweensaidexcesscurrent-operated device and spring for holding the latternormally in tension, substantially as described.

In witness whereof I hereunto subscribe my name this 28th day ofNovember, A. D.

CHARLES A. ROLFE.

Witnesses:

A. MILLER BELFIELD, HARVEY L. HANsoN.

